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    Development of a Tannic Acid-Gelatin Modified Filter Paper Membrane for Trace Lead Detection in Water
    (2026-06-16)
    Rattanadechawan, Arinrada
    ;
    Choengchan, Nathawut
    ;
    Mantim, Thitirat
    ;
    Donpudsa, Suchao
    ;
    Karuwan, Chanpen
    A novel membrane-based solid-phase extraction (SPE) device was developed using cellulose filter paper modified with a tannic acid–gelatin (TA/GE) composite for the preconcentration of lead (Pb(II)) ions from aqueous samples. The TA/GE sorbent layer was fabricated via cross-linking gelatin with tannic acid at pH 9, forming a stable, partially insoluble network that enhances the membrane’s mechanical strength and ion-binding capability. Characterization by SEM confirmed the successful modification, while micro-XRF analysis demonstrated the membrane’s effective adsorption and elution of Pb(II). After preconcentration, square wave anodic stripping voltammetry (SWASV) was used for quantitative determination. The method exhibited linear range of 10–100 μg·L<sup>–1</sup>, with a limit of detection (LOD) of 2.7 μg·L<sup>–1</sup>. Method validation using a certified reference material for trace metals in water produced a combined measurement uncertainty (U) of 9 μg·L<sup>–1</sup> at the 95% confidence level for a sample containing 61 μg·L<sup>–1</sup> Pb(II), showing no significant deviation from the certified value. The developed method was further applied to drinking water and river water samples, achieving recoveries of 82–110% for spiked samples. These results confirm that the TA/GE-modified membrane provides a simple, low-cost, and environmentally friendly platform for trace Pb(II) analysis, with performance meeting both WHO (10 μg·L<sup>–1</sup>) and Thailand Pollution Control Department (50 μg·L<sup>–1</sup>) regulatory standards for drinking and surface water.
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    Supramolecular electrochemical detection of bisphenol A using a melamine-functionalized reduced graphene oxide modified screen-printed electrode
    (2026-06-01)
    Thammaso, Supinya
    ;
    Kamsong, Wichayaporn
    ;
    Karuwan, Chanpen
    ;
    Saetear, Phoonthawee
    ;
    Detsri, Ekarat
    Detection of bisphenol A (BPA), an endocrine disruptor, requires rapid and reliable methods to ensure water safety. In the current work, we present a supramolecular electrochemical sensor based on a melamine-immobilized reduced graphene oxide-modified screen-printed carbon electrode (Mel-rGO SPE) for the determination of BPA. The sensing design exploits dual supramolecular interactions: hydrogen bonding between melamine's amine groups and BPA's hydroxyl moieties, and π–π stacking between their aromatic rings. While rGO significantly enhances electron transfer, these synergistic effects improve device sensitivity. A Mel-rGO SPE was fabricated using an ink-mixing approach to produce a uniform and robust sensor. BPA detection was performed using cyclic voltammetry, and the anodic peak potential was 0.32 V. The current response provided a good correlation with BPA concentrations in the range of 1–250 μM. The detection limit was low, 0.23 μM. The Mel-rGO SPE was successfully applied to determine BPA in polycarbonate bottled water. These promising results indicate that the developed sensor is an alternative device for rapid screening of BPA contamination of water samples.
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    A Screen Printed Graphene Based Electrochemical Sensor for Single Drop Analysis of Hydroquinone in Cosmetic Products
    (2019-08-01)
    Duekhuntod, Wannida
    ;
    Karuwan, Chanpen
    ;
    Tuantranont, Adisorn
    ;
    Nacapricha, Duangjai
    ;
    Teerasong, Saowapak
    A graphene modified carbon paste sensor (or so-called graphene based sensor) was developed for electrochemical detection of hydroquinone. The sensor was fast fabricated using screen-printing technique. By integrating three fundamental electrodes on a single device, the sensor is small and portable. A determination is based on a one drop analysis. A 60 μ.L-drop of sample was placed onto the sensor prior to cyclic voltammetric measurement. The method relies on green analysis since it lowers the consumption of sample and waste generation. Under the optimal conditions, a linear calibration was achieved in range of 1.0 x 10<sup>-4</sup> to 5.0 x 10<sup>-3</sup> M hydroquinone. The detection limit was 7 x 10<sup>-5</sup> M, a sensitive adequate for measuring hydroquinone in cosmetic products. The sensor provided good precision (%RSD = 2.78) and accuracy (recoveries = 87-114%), with analysis times of less than a minute. The sensor was applied to determine the presence of hydroquinone in whitening creams. The results obtained from the developed sensor satisfactorily agreed with the HPLC method, indicating the reliability of the method. Due to its advantages in terms of rapidity, low-cost and portability, the device is a viable choice for on-site screening for hydroquinone contamination in whitening products.